Melt spinning pack assembly



Jan. 13, 1970 R. G. DE CECCO ET AL 3,488,806

MELT SPINNING PACK ASSEMBLY Filed July 21. 1967 O n I I I; l

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32 M/ l2 Q4 & l5 -|6 INVENTORS RUDOLPH GUIDO DE CECCO ELDON LMHRENCE FLETCHER STANLEY DAVID WOOD BY W fia/mt%.

ATTORNEY United States Patent U..S. Cl. 188 4 Claims ABSTRACT OF THE DISCLOSURE A melt spinning apparatus, having a multi-passage spinning pack clamped in a sealed position against matlng polymer supply ports in a pump block by means of a single pack clamping screw.

Background of the invention This invention relates generally to the melt spinning of filaments from organic compositions and more particularly, to improvements in an apparatus for metering, filtering and extruding filaments from molten polymers.

The production of filaments from polymers such as polyhexamethylene adipamide, polyhexamethylene sebacamide, polyhexamethylene isothalamide, polyethylene terephthalate, polyacrylonitrile and many other polymers or mixtures thereof is well known in the art. One or more streams of molten polymer are fed to a pump block, where each stream is metered and fed to a spinning pack. In the pack, the polymer is forced through a filtering material and extruded through at least one spinneret into filaments or ribbons. In the past, it has been the practice for one molten polymer stream to be metered to one pack. The stream has then been divided and fed to a number of filter chambers in the pack to be spun through spinnerets into filaments. When a large number of filaments are spun in a pack with only one metered stream of polymer, problems occur in maintaining the denier uniformity. In addition, new types of yarns composed of bicomponent filaments or filaments produced from different polymers or copolymers are now in demand by todays markets and these new yarns require at least two polymer streams to be metered to one spinning pack. There have been various apparatus arrangements proposed to overcome these difiiculties. One such arrangement which involves the use of a rectangular spinning pack assembly with a multi-cavity filter and individual passages connecting each filter cavity to separate polymer passages in the spinning pump block has been disclosed by Tait in U.S. Patent 3,050,774. The removable spinning pack assemblies of the type disclosed by Tait have the disadvantage of requiring a plurality of holding or clamping bolts, one aligned with each passage for the purpose of sealing the filter cavity supply passage against its mating passage in the spinning block. The downtime required to change a spinning pack assembly is proportional to the number of clamping bolts that must be loosened to remove the pack and then uniformly retightened to apply substantially equal sealing pressure at each passage connection.

Summary of the invention It is an objective of this invention to provide an improved melt spinning apparatus wherein a .multi-cavity spinning pack may be quickly and easily attached to and detached from the pump block by means of a single pack screw to reduce the down time required to change the pack.

3,488,806 Patented Jan. 13, 1970 Another objective of this invention is to provide an improved melt spinning apparatus wherein a uniform sealing pressure may be applied to each of the multipassage connections between the spinning pack and pump block by means of a single clamping bolt.

The above objectives are achieved in a melt spinning apparatus that includes a multi-cavity spinning pack having an upstanding rib adapted to be received within a downwardly opening groove in a spinning block. The rib has a recess adapted to be engaged by a clamping bolt projecting into the groove and a plurality of passages, each passage connecting the front surface of the rib to a separate cavity in the spinning pack. The passage openings in the front face of the rib are spaced an equal radial distance from the central axis of the clamping bolt in a pattern for fluid tight communication with mating polymer supply ports in the groove in the block when the pack is clamped into place by tightening the clamping bolt.

Brief description of the drawings FIG. 1 is a sectioned elevation of the preferred embodiment of the spinning pack assembly of the present invention.

FIG. 2 is a sectioned end view showing the spinning pack assembly clamped in position in the pump block.

Detailed description of the preferred embodiment Referring to FIGS. 1 and 2, the spinning pack assembly includes, as the major elements thereof, a lid 10, a filter block 11, spacers 12 and 13, distribution plate 14, spinneret plate 15 and retainer 16.

The lid 10 has an upstanding rib 17 which fits in a groove 18 of a pump block 19. The groove 18 is defined by respective front and back walls 50, 52 facing respective front and back surfaces 54, 56 of rib 17 (FIG. 2). The spinning pack assembly is held in place by a single pack bolt 20 in a recess 21. A locating dowell 22 projecting from back Wall 52 in the pump block 19 and coaxial with bolt 20 fits into a sleeve 23 recessed in the back surface 56 of rib 17 thereby positioning the rib 17 in the groove 18. The tightened pack bolt 20 compresses eight copper gaskets 24 coaxial with passages 26 around eight polymer supply ports 25 equidistant apart in a circle i.e. equispaced radially around and spaced an equal radial distance from the central axis of the locating dowel 22. Each flow passage 26 is aligned with a supply port 25 and feeds an individual filter chamber 27. A self-sealing gasket 28 of the type shown by Gill et al. in US. 2,980,284 fits in each filter chamber 27 between the lid 10 and filter block 11. A filter media 29 in the filter chamber 27 has a top screen 30 resting on top of the filter media 29 and b ttom 1 screen 31 held in place by a retaining ring 32.

Each filter chamber 27 is round in horizontal cross section and feeds intoa zone 33 between the filter block 11 and the distribution plate 14 through a pattern of equidimensional apertures 34. A screen 35 enclosed by a gasket 36 fits in the zone 33 in the opening in the spacer 12. Distribution plate 14 is provided with a pattern of apertures 37 feeding from the zone 33. The apertures 37 feed into a further zone 38 in an opening in the spacer 13 between the distribution plate 14 and the spinneret plate 15. A screen 39 enclosed by a gasket 40 fits in the zone 38. The spinneret plate 15 is provided with orifices 41 feeding from the zone 38.

' The spinneret plate 15 is held to the distribution plate 14 and the filter block 11 by three spinneret bolts 42. Tightening these bolts 42 compresses the gaskets 36 and 40 to ensure a seal between the adjacent zones. Two socket head cap screws 43 hold the retainer 16 to the spinneret plate 15. The whole assembly is held together with a plurality of bolts 44. These bolts 44 are tightened in a criss-cross pattern to a prescribed torque in a series of stages.

In operation, eight metered streams of molten polymer are fed to the spinning pack. The streams may be the same or different polymers from one or more sources with pressures as high as 12,000 lbs./sq. in. The pump block and polymer conduit system are kept at a constant temperature to keep the degradation of the molten polymer to a minimum. The molten polymer arriving at the spinning pack has the same thermal history. While it is understood that this term implies equal time of exposure of two or more polymer streamlets to the same temperature, the latter does not necessarily have to be constant. For instance, if the temperature is allowed to vary with time, equal thermal history for a given group of streamlets can still be achieved, provided each is exposed to the same variations, and the exposure is for the same length of time at each temperature value.

The eight metered streams enter the spinning pack from the parts 25, feed through the flow passages 26 into the filter chambers 27. The polymer then passes through the filter media 29, into apertures 34 in the filter block 11. From the apertures 34, the polymer passes through screens 35 in zone 33, through apertures 37 in the distribution plate 14, through another set of screens 39 in zone 38 and is finally extruded through orifices 41 in the spinneret plate 15.

To replace the spinning pack, the eight metered streams are shut off, and the pack is removed by releasing the pack bolt 20. This unseats the eight gaskets 24 and allows the spinning pack to be Withdrawn from dowel 22 then downward. In the insertion of a clean pack, a preheated pack is raised so the rib 17 of the lid fits into the groove 18 of the pump block 19. The sleeve 23 is fitted over the locating dowel 22 on the pump block 19 i.e. in telescoping engagement, and the pack bolt 20 is tightened until the gaskets 24 are fully compressed. The polymer streams are then turned on to allow the polymer to flow into the filter chambers 27.

Whereas, in the illustrated embodiment, eight passages 26 are equispaced radially about and located an equal radial distance from the central axis of bolt 20; it has been found that the ports need not be equispaced radially, but need only be located an equal radial distance from the central axis of bolt 20 so that the compressive forces are applied substantially equally to the mating ports and passages when the pack bolt 20 is tightened. If a central locating dowel 22 forms part of this apparatus, the forces should be applied substantially equally about the central locating dowel 22.

Bicomponent filaments are spun with this spinning pack by feeding the four filter cavities 27 on one side of the spinning pack with one of the polymers, and the four filter cavities 27 on the other side of the spinning pack with the other polymer and spinning the two polymers together to form a bicomponent filament through a special spinneret plate and distribution plate.

In this design of spinning pack, the eight metered streams allow a constant denier per filament on the overall spinning pack and a high density of filaments per unit of spinning area is obtained. Yarns with deniers as low as 30 and as high as 260 have been spun using this pack. Small changes in denier are made by varying the polymer flow in the metered streams. This is done by varying the speed of the meter pumps and no replacement of the spinneret plate is required until the changes become large. Also, the possibility of stagnant areas in the polymer streams is substantially eliminated. Throughputs of 28 lbs. per hour per spinning pack have been obtained in trials of this pack with nylon 66 polymer from a single source and improved denier uniformity of filaments spun as noted.

It is apparent that changes in the number of filtration areas per spinning pack, and the number of metered streams passing into the spinning pack through the multiple ports may be made, and modifications may also be made in the disclosed spinning pack without any of the changes or modifications departing from the spirit of the present invention.

What is claimed is:

l. A melt spinning apppa-ratus comprising:

(a) a multi-cavity spinning pack including a lid with an upstanding rib, said rib having front and back surfaces, there being a bolt accommodating recess in said front surface, said lid having a plurality of through passages, each passage connecting a cavity and said back surface; and

(b) a spinning block having a downwardly opening groove defining front and back walls in said block, said groove being adapted to recive said rib, said block having a bolt projecting from said front wall, said bolt being adapted to axially engage said recess and clamp said back surface to said back wall, there being a plurality of ports in said back wall mating with said passages for supplying molten material to said spinning pack, said passages being spaced an equal radial distance from the central axis of the bolt.

2. The apparatus of claim 1 wherein is provided a sealing gasket between each port and passage.

3. The apparatus of claim 1 wherin said spinning block is provided with a dowel for locating said rib in said groove, said dowel projecting from said back wall and being coaxial with said bolt, there being a recessed sleeve in the back surface of the rib for telescoping engagement with said dowel.

4. The apparatus of claim 1 wherein said passages in said back surface are equispaced radially about the central axis of said bolt.

References Cited UNITED STATES PATENTS 8/1962 Tait. 5/1968 Wells. 

